Refrigeration



- Jan. 30, 1945. R. s. NELSON REFRIGERATION Filed March 22, 1939 8Sheets-Sheet l Rudolph 6. Nelson I ATTORNEY Jan.30, 1945. 'R. s. NELSON2,368,374

REFRIGERATION I Filed March 22, 1939 a Sheets-Sheet 2 4o 22 C ZlINVENTOR Rudolph s. JVelson MWSM ATTORNEY Jan. 30, 1945. R, s, NELSCQN2,368,374

' REFRIGERATION Filed March 22, 1939 8 Sheets-Sheet 3 INVENTOR ATTORNEYQ Rudolph Nelson Jan. 30, 1945.

R. s. NELSON REFRIGERATION Filed March 22, 1939 8 Sheets-Sheet 4 '65as"! C I 74 88 AL a4 65 I 8a INVENTOR ATTORNEY Jan. 30, 1945. R NELSON2,368,374 I REFRIGERATION Filed Maxch 22, 1939 8 Sheets-Sheet 5 INVENTORRudolph 6. Ne lson ATTORNEY 1 R. S. NELSON Jan. 30, 1945.

REFRIGERATION Filed March 22, 19:59

8 Sheets-Sheet 6 lNVENTO R 6. jVelson ATTORNEY R. S. NELSONREFRIGERATION Jan. 30, 1945.

Filed March 22, 1933 8 Sheds-Sheet 7 Illllll lllllllj- I I l l l l II II[III I I] llllll llllll INVENTOR I 1 II It llIlll llllll I II lllllllHill ATTORNEjY Jan. 30, 1945. R. s. NELSON 2,368,374

REFRIGERATION Filed March 22, 1939 8 SheetS Sheet 8 IOO' INVENTOR ATTORNEY Patented Jan. 30, 1945 REFRIGERATION Rudolph S. Nelson, Larchinont,N. Y., assignor'to The Hoover Company, North Canton, Ohio ApplicationMarch 22, 1939, Serial No. 63,527

21 Claims. This invention relates to absorption refrigerating apparatus,and more particularly, to an ap-' paratus of the kind employing inertgas and in which the absorber as well as the condenser is constructedand arranged to be cooled directly by the surrounding air. The presentapplication is a continuation-in-part of my abandoned copendingapplication Serial #685,037, filed August 14, 1933, entitled Continuousabsorption refrigerating apparatus.

Previous attempt to develop large capacity air-cooled absorptionrefrigeration apparatus operated solely by heat and utilizing an inertpressure equalizing medium have not been entlrely successful. Theoutstanding reason for this was the difliculty encountered in obtainingadequate circulation of the pressure equalizing medium through itscircuit. Another very troublesome problem was the design and arrangementof the absorber within a cabinet .of a. household refrigerator in such away as to obtain ade- For example, when using the surrounding air as thecooling medium it is necessary to provide a construction which willmaintain a desired capacity and a maximum efliciency over a range ofcooling air temperature varying between 60 and 130 F.

It is accordingly an object of the present invention to provide athree-fluid continuous refrigeration apparatus having an air cooledcondenser and an air cooled absorber which is so constructed andarranged that an adequate circulation of the inert gas is alwaysobtained, and such that the heat of absorption and the heat ofcondensation is dissipated to the surrounding air without curtailingcapacity and regardless of the temperature of the available cooling air.

A further object is to so position the parts of the apparatus withrespect to one another that the same may be constructed as a. unit,charged and tested, and then inserted directly into a refrigeratorcabinet with the heat absorbing portion extending into the food storagecompartment, and with a part of theheat dissipating portions of theapparatus underlying the storage compartment, and at least a portion ofthe remainder overlying this compartment.

Another object of the invention is to arrange the various major portionsof the apparatus in superimposed planes in order to reduce thehorizontal cross-sectional area of a refrigerator cabinet at the expenseof the vertical height in order to increase the vertical length of thecooling air flue so as to obtain a maximum flow of cooling air.

Another object of the invention is to make the condenser and theabsorber into a sinuous conduit, the various legs 'or branches of whichare located in substantiallythe same plane, and then to so position suchabsorber or condenser element in the apparatus compartment of therefrigerator cabinet as to obtain the most compact assembly and at thesame time to obtain a most efficient and maximumfiow of cooling airthereover.

Still another very important object of the invention is to provide meansfor increasing the flow of the inert gas through the absorber andevaporator notwithstanding the increased length of this circuitnecessitated by the construction adopted in certain modifications of myinvention. More specifically, it is an object to obtain an increasedflow without introducing any moving parts within the system. Moreover,due to my novel arrangement of certain elements, I am enabled to obtainan increase in the flow of inert gas by making use of heat which waspreviously 25 a total loss, and while increasing the efliciency of thesystem in other respects, as will become apparent from the detaileddescription to follow.

Another object of the invention is to promote the circulation of theinert gas between the absorber and evaporator in two ways, both of whichwere unknown prior to my invention, and the efiect of each of which isadditive to the efi'ect heretofore relied upon to circulate the inertgas. More specifically, it is an object of the invention to promote thecirculation of the inert gas by adding heat to an ascending columnthereof; and secondly, to cool another descending column thereoi to thesame or greater extent than the ascending column is heated. The heatingof the ascending column is preferably accomplished by transferring theheat of rectification thereto, while the cooling of the descendingcolumn may be obtained by passing the gas in heat exchange 1 5 of inertgas.

A still further object of the .invention i to so construct and 'locateboth the absorber and the condenser in the path of the cooling air thata given portion of the air stream passes over each of the heatdissipating elements but a single time. Furthermore, these elements areso arranged that approximately the same amount of cooling air flows overall, portions of the same, and so that air at substantially the sametemperature initially comes into contact with certain portions of theseelements.

Still another important feature of the present invention is theprovision of a multiple stage absorber such that the normal operatingtemperatures of the first and last stages is not much higher than thecooling air temperature passing thereover, while the temperature of theintermediate stage or stages is much higher. According to the presentinvention, this result is accomplished in part by cooling the inert gasout of contact with the absorption liquid as it passes from certainstages to others. By the first and last stages it will be understoodthat I mean those stages in which the inert gas first and last contactsthe solution.

More particularly, it is an object of the invention to operate the firstand last stages of the absorber at lower temperatures than anintermediate stage in order to obtain more efficient absorption. Thetemperature differential between the absorber stages is obtained in partby cooling the inert gas and refrigerant mixture out of contact with theabsorption liquid as it is conducted from one stage to another stage.

Another object is to provide a system having a I very great capacitywithout employing large sized component element which are inherentlyinemcient. More particularly, it is an object to provide a system inwhich certain elements are employed in duplicate to avoid the lossesincident to the use of large sized elements. ,It will thus be apparentthat I am able to keep the weight and cost of the materials down to aminimum because the thickness of the tubing walls necessary to withstandthe system pressures increases rapidlyprovided with heat radiating finsto increase the area of that portion of the apparatus without undulyincreasing the length and the weight of the conduits.

A further object of the invention is the provision of a novel gas heatexchanger so conitructed as to serve as a part of the absorber, and as asolution reservoir. This reservoir functions not only to store theexcess solution which should be present in other than the boiler orabsorber of thesystem for efficient operation, but also to maintain aproper solution level in the boiler assembly. Moreover, the heatexchanger is so constructed that residue, unevaporated liquid from theevaporator is returned to the boiler assembly therethrough thuseliminating an independent drain connection as heretofore.

Another object is to improve the rectifier and to provide a constructionwhereby the heat of rectification is utilized for a useful purpose.

' tain novel features of the arrangement and construction of parts aswill become apparent hereinafter from a consideration of the followingdetailed description taken in connection with the accompanying drawingsin which:

Figure 1 is a rear elevational View with portions broken away forclarity and showing a large capacity refrigerator according to thisinvention.

Figure 2 is a side elevational view of'Figure l with the near side wallbroken away to show the arrangement of the parts with respect to thecabinet and food compartment.

Figure 3 is a schematic representation of the apparatus shown in Figures1 and 2.

Figure 4 is a side elevational viewpartly in section showing a secondembodiment of the invention.

Figure 5 is a schematic representation of the apparatus shown in Figure4.

Figure 6 is a side elevational view partly in section of a thirdembodiment of the invention.

Figure 7 is a schematic representation of the apparatus shown in Figure6.

Figure 8 is a fragmentary elevational view on line 88 of Figure 6showing in greater detail .how the various branches and the fins thereonare angularly related.

of a slightly modified embodiment of the form shown in Figs. 6 and 7.

Referring now to the embodiment shown in Figures 1 to 3, it will beobserved that a refrigerator cabinet I is shown having an insulated foodcompartment ll closed at its front by a door l2. The sides of the foodcompartment extend downwardly as at 13 to enclose a refrigerationapparatus compartment and air fiue ll. of the cabinet also extendrearwardly to form a vertical air fllue I5. extending for the full widthand full height of the cabinet. This air flue is preferably closed atits back by-a panel I 6 for utilitarian and appearance purposes. Aremovable panel or door 11 serve to close the front of the apparatuscompartment. The cabinet is supported on a pedestal l8 having an airopening IS in its top, and cutaway portions at its side as shown toadmit cooling air to compartment I 4.

The side walls of the cabinet also extend slightly above the foodcompartment, and are perforated as at 20 to admit additional cooling airto this compartment. The front, top portion of this compartment may beclosed by an imperforate panel 2 I, while the rearmost portion iscovered by a perforated panel 22 through which all the cooling airdischarges back into the room.

In order that the drawings may not be unduly multiplied, it will beunderstood that the vertical air flue l5 has been shown to beconsiderably deeper than it would be made in practice, and certain ofthe conduits would be brought more nearly into a common plane.

Passing now to the schematic representation in Figure-3, theconstruction and mode of operation of my novel system will be describedafter which I will proceed to a description of the manner in which thisapparatus is disposed within the cabinet.

As is suggested by a cursory inspection of Fi ure 3, a preferredarrangement of my system includes two duplicate systems joined by acommon evaporator and gas heat exchanger. Thus Still other objects andadvantages reside in certhere are two boiler assemblies, two absorberassemblies, and two condensers. The corresponding duplicate elementswill be referred to The side walls principal elements, and an inert gastween the absorber andthe evaporator.

- changer is provided with a central conduit 3| aseasvs v hereinafter bythe same characters difiering only in the use of a prime on certainthereof.

Referring now to the lefthandhalf of Figure 3.

assembly A, gasheat exchanger H, and evaporator E. These vessels areconnected in circuit by suitable conduits to provide a hermeticallysealed system having an absorption circuit between the boiler assemblyand the absorber assembly, a re-. frigerant circuit, including all ofthe aforesaid circuit be- The system may be charged with any suitabfluids as for example ammonia as a refrigerant, water as the absorptionsolution, and hydrogen as the inert gas.

The boiler assembly includes a main refrigerant distillation chamber 23which may have a combustion chamber positioned centrally thereof andadapted tobe heated by a gas burner or other suitable source of heat.This chamberis provided with a vapor lift pump 24 of known form whichextegnds upwardly above the chamber and discharges nto the gasseparation chamber S. When heat is applied to the boiler, refrigerantvapor is liberated which collects at the base of the pump and serves toelevate absorp tion liquid from which refrigerant vapor has 7 beendistilled therethrough. The liquid so elethree stages which aredesignated by the numerals 33, 34 and 85. Each stage is preferablyconstructed from tubular elements suitably secured together as bywelding, and is provided with heat radiating fins extending inagenerallyvertical direction when positioned within the refrigeratorcabinet. As will be noted from Figures 1 and 2, the branches of eachabsorber stage are located substantially parallel to one another and inthe same plane. Each absorberstage is also preferably inclined slightlyto the horizontal sufiiciently to allow the absorption solution to newdownwardly therethrough by gravity,- and to this vated flows downwardlyinto the gas separation chamber while the refrigerant vapor passesdirectly into conduit 25, which leads into the uppermost end Bfcondenser C. p t

The condenser comprises a series of conduits which are. provided withheat dissipating fins to facilitate the cooling of the same. As a resultof this cooling action, the vapor' liquefies and flows by gravitythrough conduit 26 into the top of evaporator vessel E.

The evaporator may be made in any desired manner, but as hereinillustrated, comprises a large diameter, tubular vessel 21 closed at itsupper and lower ends, and provided interiorly with a series of staggeredsubstantially horizontally positioned baftle members 28, and a centralvertical partition 29. The liquid refrigerant. discharges onto theuppermost plate and gradually trickles from one plate to another whileevaporating into the inert gas with which the vessel is filled, thusproducing refrigeration.

The resultant mixture of inert gas and refrigerant vapor is led from theevaporator into the gas heat exchanger H through conduit 30. The heatexchanger preferably extends from the general level of the evaporator toa point intermediate the top and bottom of apparatus compartment M. Theupper portion of the heat exof heat conducting material through whichthe vapor and inert gas mixture is conducted into the lower portion ofthe exchanger. The, outer shell of the exchanger is extended downwardlyto a point adjacent the level of the boiler assembly. The lowermostportion serves as a solution reservoir 32, and also as a part of theabsorber, as will be more fully explained presently. The reservoir isconnected to the heat exchanger proper byconduit 32a which conducts thelean as from conduit 3| over the solution in reservoir 32 and into thefirst stages 33 and 33' ofthe absorbers.v Conduit 32a further serves toconduct residue liquid from the evaporator and the heat exchanger to thesolution reservoir.

end, each branch of each stage may be individually inclined slightlydownwardly.

Several stages of the absorber are connected in series so that the inertgas fiows first-through section 33, then through intermediate stage 34,and finally through stage 35.. Thus the inert gas laden with ammoniavapor passes from heat exchanger H through conduit 36 to the firstabsorber stage 33. The gas from which somerefrigerant vapor has beenremoved then passes through conduit 31 into intermediate stage 33 of theabsorber. Conduit 31 may be provided with heat radiating fins to coolthe gas mixture before it enters the intermediate stage.

The major portion of the refrigerant vapor is absorbed from the inertgas as it passes through the intermediate stage, and this stage mayaccordingly be made larger than the first and last stages. As a resultof the large amount of absoxption taking lace in this stage, the samebecomes so warm from the heat of absorption that complete absorption ofthe vapor cannot take place. his therefore desirable to cool the inertgas before the same enters the last stage in order that the remainingportion of the refrigerant vapor may be stripped from the inert gas.

To accomplish this expeditiously, I prefer to conduct the heated inertgas through an inverted U- shaped conduit 38, the opposite ends of whichare connected to thedischarge end of stage 34 and the inlet end of stage35. The inlet leg 39 may extend upwardly along one side portion of; airflue l5. At the top of the air fiue a horizontal order that the heat ofcondensation of the water vapor may be utilized for a useful purpose, Iprefer to pass a portion 26 of vapor conduit 25 through a rising part ofconduit 39 forming a part of the inert gas circuit. Inasmuch as theinert gas, though warm, is considerably cooler than the water vaporwithin conduit 26, the water vapor is cooled below the condensationtemperature, and the inert gas is heated. The condensed water vaporflows back into the gas separation chamber S leaving substantially purerefrigerant vapor flowing to the condenser.

The heat of rectification serves to heat the inert gas considerably andthus causes the same to expand and rise rapidly in conduit 39. Sinceconduits 40 and 4! are positioned directly in the path of the coolingair in flue l5, and these con- As illustrated, absorber assembly Acomprises duits are preferably provided with heat radiating fins, theheat of rectification, as well as the heat of absorption present in theinert gas, is dissipated to the atmosphere. Consequently the temperatureof the gas as it enters stage 35 is slight above that of the coolingair.

Moreover, due to the increased specific gravity of the gas in conduit4!, the gas tends to fall much faster than it would if it had not beencooled. By virtue of the use of inverted U-conduit 38, it is apparentthat the inert gas flow is ,assisted to a considerable degree by theheating of the gas in a rising portion of the gas circuit and cooled ina descending portion. And of course this heating and cooling is inaddition to the heating and cooling of different portions of the circuitelsewhere in the system heretofore relied upon to assist thecirculation.

The very cool inert gas carrying a small amount of refrigerant vaporthen flows through the last stage 35 in contact with the leanestabsorption solution and in counterflow thereto, as will be explainedpresently. The substantially pure inert gas thus obtained then flowsthrough conduit 42 into passage 43 of the gas heat exchanger. As thelean inert gas passes upwardly, it is cooled by the cold inert gasflowing downwardly through conduit 3|, after which the lean gas passesback into the bottom of evaporator E through conduit 44.

The lean absorption solution flows from gas.

separation chamber S through conduit 45 and into the top of absorberstage 35. This lean solution flows through stage 35 by gravity, and theninto intermediate stage 34 through conduit 46, and finally throughconduit 41 into the top of the last stage 33. After traversing stage 33the solution flows to reservoir 32 through conduit 48. Conduit 49 leadsthe enriched solution back to the boiler and includes a solution heatexchanger 50 intermediate its ends. The lean solution conduit 45 also isconnected to this heat exchanger, as illustrated.

It will now be understood that the rich inert gas first contactsabsorption solution in the reservoir at the bottom of the gas heatexchanger.

In spite of the fact that the heat exchanger contains rich solution, aconsiderable amount of additional refrigerant is absorbed because therefrigerant vapor carried by the inert gas and flow-v idue liquidoverlying from the evaporator to passthrough chamber 43 and to flow intoreservoir 32 but prevents the passage of inert gas between the twopassageways of the heat exchanger. By virtue of this construction,residue liquid not evaporated in the evaporator overflows throughconduit 44, passes through chamber 43 of the heat exchanger, throughgooseneck 5|, into the reservoir 32, and finally back to the boiler.This return of residue liquid is accomplished without employing anadditional drain conduit and without affecting the operation of theabsorber or other portions of the apparatus.

Since the righthand portion of the apparatus is identical inconstruction and functions with the corresponding portion of theapparatus shown on the left hand side of Figure 3, this part of isdivided and part flows into the bottom stage of absorber A. After all ofthe refrigerant vapor has been absorbed, the resultant lean gas returnsto the gas heat exchanger where it is mixed with the inert gas from theabsorber in the other half of the apparatus and is conveyed back to theinlet of the evaporator.

Thus. it will be appreciated'that there are two parallel absorptionsolution circuits, two parallel refrigerant circuits, and two parallelinert gas circuits, and that each of these parallel circuits overlapwith the other in part Passing now to a more careful consideration ofFigures 1 and 2, it will be noted that the apparatus, when viewed fromthe side, has the general appearance of the letter E. The top leg of theE comprises the condensers C and C. The lower leg consists primarily ofthe several absorber stages, while the central portion of the letter isrepresented by the evaporator and the attached ice tray housing-5 l Thecondensers are L-shaped with one leg ex.- tending vertically downwardlyinto the rear air flue, while the other leg extends substantiallyhorizontally above the food compartment. Each condenser consists of aplurality of horizontally positioned conduits .52 provided with heatradiating fins 53 extending transversely thereof. The

tubes are connected together at their ends by headers 54. The verticalleg of the condenser is cooled primarily by the air flowing through theair flue I 5, while the horizontal leg is cooled principally by airentering through perforations 20 which passes over the condenser legsand out through grille 22. Although the condensers have been shown assuperimposed, it will be understood that each condenser could bearranged to extend only half way across the cabinet so that the onecondenser might be placed on one side of the flue and the other on theopposite side.

It will be observed from Figure 1 that descend-.

ing legs 4| and 4i of the inert gas circuit are provided with inclinedheat radiating fins 55 and 55'. Figure 2 also shows that the horizontalportions 40 and4ll' of this circuit are also provided with fins 56 and56 respectively.

Figure 2 depicts the arrangement of the several stages of the absorberin the apparatus compartment and the manner in which the alternatestages are staggered with respect to one another to permit of a morecompact arrangement as well as to reduce the resistance to the flow ofcooling air. Each stage is made up of a sinuou conduit,

all branches of which are located in the same plane which is inclined tothe horizontal only sufficiently to prevent .the absorption liquid fromcollecting in any substantial amount and in order to prevent the conduitfrom becoming locked due to a slightly unlevel setting of therefrigerator.

Each branch is provided with a large number of In operation the highertemperature of the heat thereof to the other.

. 2,868,374 ments. This air flows upwardly over all portions oftheabsorber and upwardly through the air flue l and over the conduittherein, and finally over the condensers at the top of the flue. As willbe noted from Figure 1, the boiler and solution heat exchangers arepositioned to one side of the cabinet so as not to interfere with theair flow, and it will b understood that these elements are suitablyencased in insulating material (not shown for purposes of clarity) toprevent loss of heat therefrom. This insulation casing includes thevapor lift pump and the gas separator, and may include vertical legs 39and 39' of the inert gas circuit, or at least that portion thereof inwhich the rectifiers are housed.

Figures 4 and 5 show a simplified manner of constructing an absorptionrefrigeration apparatus in accordance with the broad principles of myinvention. This system is best adapted for use in refrigerators ofmedium capacity, and differs primarily from the form shown in Figures 1to 3 in having no duplicate principal vessels, and in employing asimplified two-stage absorber.

The refrigerator cabinet is substantially identical with that shown inFigure 1, and comprises an insulated food compartment 60 having a door8l. This compartment is supported sufilciently above the notched base 62to provide a combined air fine and apparatus compartment 63 whichcommunicates at its rear with a vertical air flue 64 extending for the,full height of the cabinet. This latter flue also communicates with athird fine 65 located above the food compartment'and having air inletopenings 66 in its sides and air discharge openings 61 in its top. Apanel 68 is removably secured to the back of the vertical air flue. a

The refrigeration apparatus proper comprises a boiler B, a gasseparation chamber S, a condenser C, an evaporator E, a ga heatexchanger H, and a. two-stage absorber A. The boiler assembly, includinga vapor lift pump 69 and gas separation chamber S, is identical withthat shown in Figure 1, and will not be described in detail. A tube 10passes centrally through the boiler and provides a combustion chamberfor gas ,burner 1| positioned at the front end thereof. A

combustion gas flue 12 extend from the opposite end of the chamber anddischarges the gases into air flue 64 adjacent the top thereof.

The refrigerant vapors generated in the boiler pass from the gasseparation chamber through conduit '13 which leads into the top of thecondenser. A co'nsiderable portion of conduit 13 is located interiorlyof a part of the inert gas circuit to assist the circulation of theinert gas and to rectify the absorption solution vapors present in therefrigerant vapor.

Condenser C consists of a plurality of conduits secured together attheir opposite ends to form a continuous fluid passageway from one endEach of the branches is parallel to the others, and all are located insubstantially the same plane. Each branch is provided with fins 14. Thecondenser as a whole is located directly above the food compartment, andis inclined so that the inlet end is at a higher elevation than thedischarge end. It will also be noted that this arrangement of thecondenser serves to distribute the air rising through the air flueequitably over all portions of the condenser as it passes upwardlytherethrough. Additional cooling air enters through openings 66 byreason of the convection currents set up by the condenser, as will bereadily understood. A

conduit 15 conducts the condensate from the condenser to the box coolingcol-l I6 of evaporator E.

By reason of the location of the-condenser above the food compartment, Iam enabled to position the evaporator at the uppermost part of the foodcompartment and to supply liquid refrlgerant to the top thereof bygravity. Moreover, this arrangement permits the use of a condenserofadequate size to condensate the refrigerant vapor at high roomtemperatures without obstructing the upper end of the vertical air flueand without lowering the evaporator.

The evaporator is preferably formed of tubing bent into an appropriateshape to cool a sharp freezing chamber formed by a casing 11 enclosingall ortions of the evaporator coil except the uppermost conduit 16. Thecasing completely surrounds portion 18 of the evaporator coil and aircooled absorber A in a closed inert gas circuit.

This circuit will be best understood by reference to Figure 5, and willbe described by following the flow of the inert gas as it leaves the boxcooling conduit 16 of the evaporator. Gas flows from the evaporatorthrough conduit into the inner passage 8! of the gas heat exchanger H.From the bottom of the heat exchanger the inert gas enters the top ofabsorber A through conduit 82. The absorber comprises two sections orstages 83 and 84 which are similar in construction and arrangement.

. After the inert gas has passed downwardly through stage 83, it flowsthrough the inverted U-shapedconduit 85 which extends up through therear air flue and includes legs 86, 81, and a horizontal connectingconduit 88. The inert gas flows upwardly through leg 86, through conduit88, and downwardly through leg 81 into the lowermost portion of section84 of the absorber.

; After passing upwardly through this absorber section, the gas flowsinto the outer passage 89 of the gas heat exchanger through conduit 9|},and back into the bottom of the evaporator through conduit 9|, therebycompleting its circuit.

Each stage of the'absorber consists of a plurality of straight conduitsections 92 connected at their ends to provide a continuous fluidpassageway provided on the exterior thereof with heat radiating fins 93.Each branch of the absorber is not only generally parallel to theothers, but is preferably inclined slightly to the horizontal to providea continuous downward path of flow for the absorption solution. FromFigure 4 it will be seen that all branches are located in substantiallythe same plane, and that the entire absorber vessel is inclined slightlyto the horizontal. At least a, portion of stage 83 is located directlyin the vertical air flue while the remainder of I the absorber ispositioned sufllciently below the bottom of the food compartment topermit a free flow of cooling air upwardly through all portions of theabsorber and then laterally to the vertical air flue without againstriking any part of the absorber.

Referring now to the absorption solution circuit, it willbe understoodthat the weak solution, after being elevated through pump 69 into thegas separation chamber, flows therefrom through conduit 92 into thesolution heat exchanger 93,

part of absorber stage 83. The weak solution then flows downwardly bygravity in parallel with the inert gas, and through liquid seal .conduit95 into the top of absorber stage 84. The

partially enriched absorption solution flows in counterflow to the inertgas through this stage. By the time the solution has reached the bottomof this stage, it has become saturated with refrigerant vapor, andreturns to the boiler through conduit 94, solution reservoir 91, conduit98, solution heat exchanger 93 and conduit 99.

From the foregoing it will be apparent that this embodiment functions insubstantially the same manner as the preferred construction with theexception that there are no parallel fluid circuits in the same sense asin the preferred form, and the construction and mode of operation of themulti-stage absorber is somewhat difierent. It will be manifest however,that the rich inert gas and absorption solution flow in parallel inabsorber stage 83 after which the warm gas is led upwardly throughinverted U-shaped conduit 85 for identically the same reasons as havebeen explained in detail hereinabove in connection with Figures 1 to 3.The cooled inert gas then flows in counterflow with the absorptionliquid through the last absorber stage 84 where-the remainingrefrigerant is stripped from the inert gas.

A still more simplified embodiment of the invention is shown in Figures6 and '7. Thi form has been found quite adequate for refrigerators ofsmaller capacity although it will be understood that this form is notlimited to such small caacity, but rather that it has been found moreefficient in the smaller sizes.

This embodiment is similar to that shown in Figures 4 and 5 but differstherefrom primarily in the use of a single stage air-cooled absorber inwhich there is no interstage cooling of the inrt gas out of contact withthe absorption liquid. Thus, the inverted U-shaped conduit is eliminatedtogether with its two principal functions of facilitating thecirculation of the inert gas, and of rectifying the refrigerant vaporsflowing to the condenser. In machines of smaller capacity, it is notnecessary to employ an absorber having a large number of conduits.Therefore, the resistance to the gas flow is not nearly as great, andthe difference in the specific gravity of the gases in the inner andouter passages of the gas heat exchanger and other portions of the gascircuit is sufficient to provide the required gas flow between theabsorber and the evaporator.

The cabinet I is identical with that of Figure 4, and is provided withan insulated food compartment IOI, an apparatus compartment I02therebelow, a rear vertical air flue I03 and an overlying ventilatedcondenser-compartment I04.

The refrigeration apparatus includes as principal vessels a boiler B, agas separation chamber S, a condenser C, an evaporator E, a gas heatexchanger H, and a single stage air-cooled absorber A. The boilerassembly, condenser, evaporator, gas heat exchanger,- and solutionreservoir are substantially identical with the corresponding elements ofthe second embodiment and therefore it will not benecessary to describethese elements in detail.

Absorber A consists of a plurality of parallel branches I05 which lie inthe same general plane, and each of which is inclined slightly to thehorizontal when in operative position. The absorber vessel as a whole ispositioned beneath the food compartment with the rearmost branches inthe vertical air flue and at a higher elevation than theremainingbranches. The absorber is located far enough below the foodcompartment to permil; thecooling air to rise vertically through theabsorber and then pass laterally into the rear fiue Without againcontacting the absorber.

The ammonia vapor produced in the boiler elevates lean absorptionsolution through vapor lift pump into the top of the gas separationchamber and then passes through conduit I06 into the top of thecondenser. Conduit I06 is provided with fins I07 to provide a rectifierR which functions to prevent water vapor from flowing to the condenser.

After the refrigerant vapor has been liquefied, it flows through conduitI00 into the box cooling conduit I09 of evaporator E. As the refrigerantflows downwardly through the evaporator, it evaporates into the inertgas flowing upwardly therethrough, thereb producing refrigeration. Theinert gas, which preferably is hydrogen or other like gas, laden withrefrigerant vapor, passes through conduit H0 into the central passageIII of the gas heat exchanger H, and from there into the lowermostportion of absorber A through conduit II2. As the gas passes upwardlythrough the absorber in counterflow with lean absorption solution, therefrigerant vapor is absorbed and the substantially pure hydrogenreturns to the evaporator through conduit II3, outer passage N4 of theheat exchanger and conduit H5.

The lean absorption solution flows by gravity from the bottom of the gasseparation chamber into the top of the absorber through conduit I I6,absorption solution heat exchanger III and conduit I I8. The leansolution then flows downwardly by gravity through the absorber andabsorbs the refrigerant vapor. The enriched solution is returned to theboiler through conduit H9, and solution heat exchanger I I1.

It will be observed that all heat rejecting parts of this apparatus,including absorber A, rectifier R, and condenser C, are air-cooled. Forthis purpose, the branches of the absorber are provided with verticallydisposed fins I22, the rectiher with inclined fins I01, and thecondenser with fins I23. It will also be noted that the box cool-. ingportion I09 of the evaporator carries fins I24 to facilitate thetransfer of heat from th box air to the refrigerant liquid.

A suitable heating means, such as gas burner I25, is properly positionedto heat the boiler. The

In order that the gas heat exchanger may not interfere with the uniformflow of cooling air over all parts of the absorber, this vessel may belocated in one corner of the flue.

Figure 8 is a fragmentary view showing in greater detail the manner inwhich the absorber in any one of the embodiments heretofore describedmay be constructed. Although the straight portions of the absorberbranches have been shown as positioned horizontally in Figures 1 to 7,it will be understood that each branch may be and preferably is inclinedslightly to the horizontal, as is more clearly illustrated in Figure 8.From this figure it will be seen that absorber branches I30, I3I and I32are inclined downwardly to insure that the absorption liquid will flowtherethrough by gravity at a desired rate. The rate of solution flow mayobviously be increased or decreased by modifying the angle ofinclination of the branches.

asoas'n The branches are provided with a. plurality of heat radiatingfins I33, I34 and I35. These fins are perpendicular to the axis of theabsorber branches. Consequently, if the branches are inclined to thehorizontal as shown in Figure 8, the fins will bei'nclined slightlytothe vertical. Since adjacent absorber branches are inclined to thehorizontal in opposite directions, it follows that the fins on adjacentbranches are inclined tothe vertical in opposite directions. This isindicated in Figure 8 wherein line I31 represents the plane of one ofthe fins I35 on branch I32 of the absorber. Line I38 represents theplane of one of the fins I34 on an adjacent absorber branch I3I, andline I36 is a vertical line drawn through the intersection of lines I31and I38. It will now be apparent that fins I35 are inclined to the rightfrom the vertical by the angle I39, while fins I34 are inclined to theleft from the vertical by the angle I40.

This inclination of the fins to the vertical is desirable because thecooling air tends to'rise vertically between adjacent fins. Theinclination of the fins causes the path of the air to be divertedslightly from the vertical, thereby resulting in more intimate wipingaction of the cooling air across the surfaces of the fins.

Figure 9 represents a slightly modified arrangement of the upper partonly of the apparatus illustrated in Figures 6 and '7. It will beunderstood that the remainder of the apparatus not illustrated in Figure9 is identical with that shown in Figures 6 and 7.

The principal difference between the arrangement of Figure 9 and thatshown vin Figures 6 and '7 is the location of a modifiedform ofcondenser in the vertical air flue. The same reference charactersdistinguished by a prime will be employed in describing Figure 9. Thesame reference characters as used in describing Figures 6 and '7, exceptthat they are distinguished by a prime character, will be employed indescribing the corresponding element in Figure 9.

Thus, a generally tubular evaporator E is shown as located in a foodcompartment IOI' of a conventional cabinet I. Box cooling conduit I09 ofthe evaporator is preferably provided with heat absorbing fins I24. Atubular, finned, aircooled condenser C is located in the topmost portionof the vertical air flue I03". The refrigerant vapor line I05 leads fromthe generator, not

. shown, to the top of the-condenser, and the vapor liquefied in thecondenser is led into the box cooling portion I 09' of the evaporatorthrough conduit I08.

The evaporator connects with the usual gas heat exchanger H, which maybe located in the rear air flue. This heat exchanger is provided wi than inner gas conduit III which is condenser.

substantially across the entire width of the air 75 nected to the boxcooling portion of the evaporator, and the bottom of the evaporatorcommunicates with the outer passage II4 of the heat exchanger.

The alternate, transversely extending branches of the condenser arelocated in two vertically extending banks I24 and I 25. It will beunderstood, of course, that banks I24 and I25 may be inclined slightlyto the vertical, if desired, in order that the condenser will extendentirely across the depth 'of the vertical air fiue, and thereby preventthe passage of some of the air through the flue without passing over thecon- Each branch of the condenser extends flue and is inclined slightlydownwardly throughout its length. Each branch, is connected at its upperend to the lower end of a corresponding branch in the'other bank. Itfollows that when the branches are connected together, a continuousfluid passageway is provided which is inclined downwardly from itsuppermost to its lowermost end.

Each condenser branch is provided with a plurality of perpendicular heatradiating fins I23. Since all the condenser branches in bank I 25 slopedownwardly in one direction, and since all the condenser branches inbank I24 slope downwardly in the opposite direction, it will be obviousthat all the fins I 23 in bank I25 are inclined slightly to the verticalin one direction, while the fins on bank I24 are inclined to thevertical in the opposite direction. It is therefore possible to extendall the branches in one bank through a plurality of elongated fins whichare common to all the branches in that bank.

As has been seen hereinabove, all parts of the apparatus are constructedof small diameter tubing of iron, steel, or other suitable material. Inlarger machines, certain of the principal elements have been duplicatedin order that the high efliciency of small sized elements may be takenadvantage of and also to reduce the Weight of the apparatus and the costof materials, as well as for other reasons explained in the foregoingdescription. If large sized vessels andtubing were employed, allportions of the fluids would not come in contact with the walls, as isdesired for proper heat transfer, and the thickness of the walls wouldhave to be increased very greatly in order to withstand the operatingpressures of the system.

Another important result of my arrangement is that the various parts arearranged in superimposed relationship. This has the advantage ofreducing the horizontal cross-sectional area of the cabinet and ofincreasing the vertical height in order to improve the flue action andthe circulation of air over the apparatus. It will also be observed thatby virtue of my novel arrangement the cooling air stream flowsvertically over all parts of any given element at substantially the sametime, and all parts of this air stream of my invention or the scope ofthe annexed claims.

I claim:

1. In an absorption refrigerating system having an absorber and anevaporator which operate at substantially the same total pressure and inwhich an auxiliary pressure equalizing medium is employed, an absorberhaving a plurality of sections, means connecting said sections to theevaporator and for causing the auxiliary pressure equalizing medium topass through said sections in parallel circuits,,each of said sectionshaving a plurality of stages and means for causing one of the stages ofeach section to operate at a higher temperature than another stagethereof.

2. In a continuous absorption refrigerating system having an absorberand an evaporator which operate at substantially the same total pressureand in which an' auxiliary pressure equalizing medium is employed, anabsorber having a pluabsorption liquid through said absorber, thearrangement being such that the auxiliary medium and the absorptionliquid flow in counter-current in certain of said stages andconcurrently in others of said stages. I

8. In a continuous absorption refrigerating system, an evaporator, anabsorber having a plurality of sections, each section having a pluralityof stages, means for circulating absorption liquid through said sectionsin parallel and in series through the stages thereof and meansforcausing an auxiliary pressure equalizing medium to circulate betweenthe evaporator and through said sections of the absorber in parallel,means connecting said stages to direct the flow of the auxiliary mediumtherethrough in series and in different sequence than the flow of theabsorption liquid therethrough.

4. That method of producing refrigeration by means of a refrigerant, anabsorbent therefor and a pressure equalizing medium which includesevaporating liquid refrigerant in the presence of pressure equalizingmedium to produce refrigeration, removing the resulting gaseous mixtureby gravity action, dividing said gravity propelled mixture into aplurality of streams, passing one of said streams into intimate contactwith and in counterflow to weak absorbent, passing another of saidstreams into intimate contact with and in counterfiow to an independentbody of absorbent whereby the refrigerant is absorbed from said pressureequalizing medium, and returning said pressure equalizing medium backinto the presence of refrigerant liquid to produce furtherrefrigeration.

5. In an absorption refrigerating system having an absorber throughwhich an absorbent medium flows and an evaporator which operates atsubstantially the same total pressure, and in which an auxiliarypressure equalizing medium is employed, said absorber having a pluralityof vessels and means connecting said vessels in parallel with theevaporator and for causing the auxiliary pressure equalizing medium topass through said evaporator and said vessels in parallel and similarcircuits, and in counterflow to the absorption medium, the circuitshaving an identical path through the evaporator.

6. An absorption regfrigeration apparatus having a multiple stageabsorber in circuit with an evaporator, means for passing an absorptionsolution through first one stage and then another stage of the absorber,means for circulating a pressure equalizin medium from said evaporatorinto intimate contact with said absorption solution, and means forconducting the pressure equalizing medium out of contact withthe-absorption liquid and into heat exchange relation with a coolingmedium before returning the same to another stage of said absorber.

'7. The method of operating an absorption rei'rigeration apparatus ofthe type having a boiler. an evaporator, a condenser and an absorberconasoasu nected in circuit and charged with a refrigerant. an absorbenttherefor and a pressure equalizing medium, which method comprisesbringing a gas-" the partially separated gaseous mixture out of contactwith said stream and into heat exchange relation with a cooling mediumexternal of said apparatus, and then returning the same into thepresence of said stream in condition to give up additional vapor to saidstream.

8. That method of producing refrigeration with apparatus of theabsorption type having a boiler, a condenser, an evaporator and anabsorber connected in circuit and charged with a refrigerant, anabsorbent medium and a pressure equalizing medium, which methodcomprises passing a gaseous mixture of relatively cold refrigerant vaporand pressure equalizing medium into contact with a stream of relativelyconcentratedabsorbent medium for the purpose of further concentratingsaid medium, then passing the gaseous mixture into contact with a leanerportion of said absorbent medium stream where additional refrigerant isabsorbed, then conducting the relatively warm partially separatedgaseous mixture out of contact with said stream and into heat exchangerelation with a cooling medium external to said apparatus to cool saidgaseous mixture, and then passing the cooled gaseous mixture back intocontact with absorbent medium to cause still further absorption of therefrigerant vapor.

9. That improvement in the art of refrigeration by means of anabsorption system of the typ having a boiler, a condenser, an evaporatorand an absorber connected in circuit, a refrigerant, an absorbent fluidand an inert gas with- 40 in said system, said circuit including a gascircuit between said absorber and evaporator, and an absorbent fluidcircuit between said boiler and absorber, said last named circuitoverlapping, in part, said gas circuit, said improvement comprisingproviding means in said gas circuit for passing a warm mixture of inertgas and refrigerant vapor out of contact with absorbent fluid and intoheat exchange relation with a medium external to said system and at alower temperature than said warm mixture of gas and vapor whereby themixture of gas and vapor is cooled, and returning the cooled mixture tosaid overlapping portion of said gas and absorbent fluid circuits incondition to give up additional vapor to said absorbent fluid.

10. That improvementin the art of refrigeration by means of anabsorption system of the type having a boiler, a condenser, anevaporator and a multiple stage absorber connected in circuit, saidsystem being charged with a refrigerant, an absorbent medium therefor,and a pressure equalizing medium, said circuit including a pressureequalizing medium circuit and an-abs rbent medium circuit which overlapin part in said absorber, said improvement comprising means forconducting a warm mixture of pressure equalizing medium and refrigerantvapor from one stage of said absorber into heat exchange relation with acolder medium external to said system for the purpose of cooling saidgaseous mixture and returning the same to another stage of said absorberin condition to give up refrigerant vapor to said absorbed medium.

11. That improvement in the art of refrigeration by means of anabsorption system of the said absorber, said improvement comprisingmeans for conducting a plurality of warm streams of pressure equalizingmedium and refrigerant out of contact with liquid absorbent i certainstages of said absorber and into heat exchange relation with a coldermedium and returning said cooled streams to other stages thereof wherebyadditional refrigerant vapor is absorbed.

12. That improvement in absorption refrigeration apparatus of the typehaving a boiler, a rectifier, an evaporator and a multi-stage absorberconnected in circuit and including an inert gas circuit between saidevaporator and absorber, which improvement comprises simultaneouslytransferring heat from said rectifier to said gas circuit at a pointbetween two absorber stages to promote the circulation of gas therein bythermosyphonic action and condensing absorbent vapor in said rectifierfor return to the boiler by gravity, and thereafter cooling said inertgas before it passes into the next absorber stage and into contact withabsorption solution.

13. An absorption refrigeration apparatus of the type having amulti-stage absorber and an evaporator in circuit therewith, means forsupplying absorption solution to each stage of said absorber for flowtherethrough, means for conducting rich inert gas from the evaporator tothe absorber and into contact with said absorption solution, and meansfor conducting inert gas from which a part of the refrigerant has beenabsorbed out of contact with said solution and into heat exchangerelation with a cooling medium, and for returning said gas to theabsorber for the removal of the remaining refrigerant by the absorptionsolution.

14. That improvement in the art of refrigeration by means of anabsorptio system of the type having a boiler, acondenser, an evaporatorand an absorber connected in circuit, a refrigerant, an absorbent fluidand an inert gas within said system, said circuit including a gascircuit between said absorber and evaporator, and an absorbent fluidcircuit between said boiler and absorber, said last named circuitoverlapping, in part, said gas circuit, said improvement comprisingmeans for conducting the inert gas out of contact with a stream ofabsorbent fluid after it has passed through the major portion of theabsorber and passing the same into heat exchange relation with a coolingmedium external to said system and for returning the cooled gas backinto contact with saidstream of absorbent fluid flowing through a minorportion of the absorber. l

15. In an absorption refrigerating apparatus, a vessel having oneportion arranged to provide a gas heat exchanger and another portion topro? vide a reservoir and gas conduit, an absorber coil including aplurality of finned directly air cooled conduit branches inclined forgravity flow of absorption solution therethrough, means connecting oneend of said absorber coil to said gas heat exchanger portion of saidvessel, and means connecting the other end of said absorber coil to saidreservoir and gas conduit portion of said vessel.

16. In an absorption refrigerating apparatus, a

vessel, means in one portion of said vessel defining a plurality of gaspaths in heat exchange relationship, the other portion of said vesselcommunicating with one of said gas paths and forming a solutionreservoir, and an absorber coil including a plurality of directly aircooled finned conduit branches having one end connected to said vesselto communicate with a gas path not in communication with said reservoirand its other and connected to said vessel to communicats with saidreservoir.

17. In an absorption refrigerating apparatus,

- an evaporator, an absorber comprising a tubular directly air cooledconduit, 8. generator, a vertically positioned vessel, means in theupper portion of said vessel providing a plurality of gas paths in heatexchange relation, the lower portion of said vesselforming a solutionreservoir and being in open communication with-one of said gas paths,means connecting said evaporator to the upper portions of said gaspaths, means connecting said generator, said reservoir and said absorberto form a solution circuit, one

end of said absorber being connected to the gas space of said reservoirand the other end being connected to the 'lower portion ofa gas path insaid vessel not in open communication with said reservoir.

18. Absorption refrigeration apparatus including an'upper condensercomprising a tubular conduit having turns in a single substantiallyhorizontal plane, a lower absorber comprising a tubular conduit coiledin a single substantially horizontal plane, and an evaporator comprisinga tubular conduit above said absorber and below said condenser, conduitmeans arranged to convey a gaseous mixture of inert gas and refrigerantvapor from said evaporator to a first part of said absorber coil,conduit means arranged to convey an absorptionsolution to said firstpart of said absorber, conduit means arranged to convey said mixture.and said absorption solution from saidiirst part of said absorber to asecond prising essentially a tubular conduit disposed in said apparatuscompartment and having a plurality of heat-dissipating conduit branchesin a single substantially horizontal plane, all of said branches beingsubstantially in parallel with respect to air flow and each of saidbranches being exposed to cooling by air of entrance temperature,unheated by previous dissipation of heat of absorption, at least a majorportion of said tubular absorber having its conduit portionsnonoverlapping with respect to air flow, conduit means providing forcirculation of an inert gas refrigerant vapor mixture through one partof said absorber in one direction and through another part of saidabsorber in another direction, and conduit means providing for flow ofan absorption solution through said parts of said absorber in the samedirection. 1

20, An absorption refrigeration system including a generator, acondenser, an evaporator, an absorber, and members connecting said partsfor circulation of refrigerant through the parts, for circulation ofabsorption liquid between the generator and the absorber and circulationof inert gas between the absorber and the evaporator, said members beingso constructed and arranged that the inert gas and absorption solutionflow in the same direction through a portion of said absorber and inopposite directions in another portion or said absorber, said absorberhaving heat rejecting surface provided by a finned conduit havingbranches all of which are in a single substantially horizontal plane,and members forming a path for upward flow of air in cooling relationwith said absorber so that all parts of the absorber are substantiallyin parallel with respect to the air flow, each of said branches beingexposed to cooling by air of entrance temperature, unheated by previousdissipation of heat or absorption.

21. An absorption refrigeration-system including a generator, acondenser, an evaporator, an absorber, and members connecting said partsfor circulation of refrigerant through the parts, for circulation ofabsorption liquid between the gen erator and the absorber andcirculation of inert gas between the absorber and the evaporator, meansfor removing inert gas from contact with solution between said portionsof said absorber and for conveying the inert gas through a path of flowin heat exchange relation with a cooling medium, said absorber includinga finned conduit having branches all of which are in a singlesubstantially horizontal plane, and members forming a path for upwardflow of air in cooling thereof are .substantially'in parallel withrespect to the air flow and each'ot said branches is exposed to coolingby air, unheated by previous dissipation of heat of absorption from said0 branches.

RUDOLPH S. NELSON.

relation with said finned conduit so that all parts

